Markus Schnorbus‡, Brian Menounos†, Arelia Schoeneberg‡, Faron Anslow‡, Georg Jost§, and Dan Moore#

‡ Pacific Climate Impacts Consortium† University of Northern British Columbia§ BC Hydro# University of British Columbia

Improvements to a Regional Hydrologic Model by Incorporating Glacier Dynamics

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CGU Annual Scientific MeetingVancouver, BCH06: Advances in Cold Regions HydrologyMay 30, 2017

Western North America Glaciers

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Western North America GlaciersDownstream Influence – August Streamflow

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Hydrology ModelVariable Infiltration Capacity (VIC) Model

Symbol Key:

P – PrecipitationE – EvaporationEt – TranspirationEC – Evaporation from canopy storageRS – Shortwave (solar) radiationRL – Longwave radiationS – Sensible heatL – Latent heatI – InfiltrationQd – Vertical drainage (percolation)

Liang et al. (1994, 1996)

• Spatially distributed hydrologic model

• Model resolves water and energy balance at a daily or sub-daily time step for each grid cell

• Accounts explicitly for topography, soil and vegetation

• Energy-balance snow model

• Applied at a resolution of 1/16-degree (~5-6 km)

• Coupled to a routing a model to simulate streamflow

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Introduction Model Study Area Calibration Verification Next Steps

VIC-GL Upgrades

Snowfall, PSublimation

QL/Ls

Snow Melt

SublimationQL/Ls

Glacier Surface Layer (Tsurf)

Glacier (isothermal at 0°C)

Sin αSin Lin Lout Qs QL Qr

Snow Layer

Ice MeltQm/Lm

dsurf

∞

where:Sin = incoming solar radiationLin = incoming longwave radiationLout = outgoing longwave radiationQs = sensible heatQL = latent heat

Tsurf = glacier surface temperaturepi = density of iceci = heat capacity of iceα = glacier albedo

Predominantly based on model of Klok and Oerlemans (2002):

Qr = heat advected from rainfallQm = energy for ice meltG = glacier heat fluxLs = latent heat of sublimationLm = latent heat of meltdsurf = thickness of glacier surface layer 5

Mass Balance Modelling

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VIC-GL UpgradesDynamics Modelling - Regional Glaciation Model

• Simulates the physics of ice flow using a numerical ice dynamics model based on a three-dimensional representation of glacier geometry

• Shallow-ice approximation and isothermal ice• Forced by an annual mass balance rate (updated annually), where Δt = 0.1 years

Jarosch et al. (2013); Clark et al. (2015)Introduction Model Study Area Calibration Verification Next Steps

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Bridge River above La Joie Dam

Downton Lake

Carpenter Lake

AndersonLake

Seton Lake

La JoieDam

TerzaghiDam

SetonDam

Study Area

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Model Calibration and Verification

Data Type Data Source Calibration VerificationNaturalized Inflow BC Hydro 1991 - 2000 1961 - 1990Snow Cover§ MODIS/Terra 2000 – 2005Evapotranspiration‡ LandFlux-EVAL 1991 – 2000Mass Balance – geodetic† UNBC 1985 – 1999Mass Balance – glaciological UNBC/UBC 1977 – 1985

Snow Water Equivalent+ BC Ministry of Environment 1995 – 2005

Glacier Area# UNBC 1985, 2000, 2005

Data Details

§ Hall, D. K. and G. A. Riggs, 2015: MODIS/Terra Snow Cover Monthly L3 Global 0.05Deg CMG, Version 6, Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: http://dx.doi.org/10.5067/MODIS/MOD10CM.006.‡ Mueller, B. et al., 2013: Benchmark products for land evapotranspiration: LandFlux-EVAL multi-dataset synthesis, Hydrol. Earth Syst. Sci., 17, 3707-3720, doi:10.5194/hess-17-3707-2013† Schiefer, E., B. Menounos, and R. Wheate, 2007: Recent volume loss of British Columbian glaciers, Canada. Geophys. Res. Lett., 34, L16503, doi:10.1029/2007GL030780.+ BC River Forecast Centre; http://bcrfc.env.gov.bc.ca/data/survey/# Bolch, T., B. Menounos, and R. Wheate, 2010: Landsat-based inventory of glaciers in western Canada, 1985–2005. Remote Sensing of Environment, 114, 127–137, doi:10.1016/j.rse.2009.08.015.

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Model PerformanceEvapotranspiration

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Model PerformanceSnow Cover Area

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Model PerformanceDischarge – Flow Duration

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Model PerformanceDischarge - Hydrograph

RBias = 0.04R2 = 0.75NSE = 0.69LNSE = 0.78KGE = 0.82

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Model VerificationSnow Water Equivalent – Manual Snow Surveys

1C38 @ 1884 mCell 368478 @ 1890 mRBias = 16%RMSE = 158 mm

1C39 @ 1393 mCell 368473 @ 1387 mRBias = 62%RMSE = 334 mm

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Model VerificationAnnual Surface Mass Balance – Bridge Glacier

Statistic Observed Simulated Error

Geodetic – 1985-1999 -8.99 -11.52 28%

Glaciological – 1977-1985 -5.53 -4.29 -23%

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Model VerificationSurface Mass Balance Gradient – Bridge Glacier, 1977-1985

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Model VerificationBasin-wide Glacier Area Change

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1985

Model VerificationGlacier Mask

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2000

Model VerificationGlacier Mask

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2005

Model VerificationGlacier Mask

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Verification - DischargeDaily Average Discharge, 1961 - 1990

-1.00

-0.50

0.00

0.50

1.00

1 2 3 4 5 6 7 8 9 10 11 12

Month

Monthly Bias

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Account for additional sources of sub-grid variability on mass balance:• Slope, aspect, shading and reflection effects on net radiation• Mechanical redistribution of snow (wind and gravity)• Account for glacier boundary layer processes (katabatic forcing)

Calibrate explicitly to gradient data (where available, e.g. higher resolution SCA) Explicit calibration of glacier outflow parameters (storage-discharge

relationship)More careful consideration of modelling domain when simulating

dynamics

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Next Steps

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Examiniation of the Pareto set indicates a clear trade-off with respect to parameter selection: Discharge ↔ Mass Balance

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ACKNOWLEDGEMENTS